The present invention relates generally to the field of automatic transmission systems and, more particularly, to a replacement intermediate shaft assembly for the Chrysler A518 and A618 transmissions. 
The intermediate shaft assembly in the aforementioned A518 and A618 transmissions (hereinafter “Chrysler transmissions”) is located within and extends through the aft transmission housing and overdrive piston retainer mounted thereon and functions generally to interconnect the reverse drum component within the transmission housing to the overdrive assembly attached to the exterior of the housing. The intermediate shaft assembly including the structural features thereof also comprises an integral segment of the transmission lubrication circuit. 
The original equipment manufacture (hereinafter “OEM) intermediate shaft assembly of the Chrysler transmissions is susceptible to premature wear on the bearing surfaces and splines, and delivers inadequate lubrication to the front planetary gears, the overdrive planetary gears, and to the overdrive support causing premature wear of surrounding parts. This is due primarily to the design of the automatic transmission fluid (hereinafter “ATF”) inlets within the OEM intermediate shaft, which fails to provide a sufficient flow of ATF to the aforementioned components under normal operating conditions. 
Thus, the present invention has been developed to resolve this problem by providing a direct replacement intermediate shaft assembly for the Chrysler transmissions, which provides improved ATF flow and delivers a sufficient flow of lubrication to the front planetary gears, the overdrive planetary gears, and other components served by the shaft lubrication circuit.  